Optical scanning device, image forming apparatus

ABSTRACT

An optical scanning device includes a light source, a scanning member, a converging lens, a first aperture, a second aperture, and a support member. The first aperture is provided between the converging lens and the scanning member and includes a first opening portion configured to restrict a beam path width in a main scanning direction of the laser beams emitted from the light source. The second aperture is provided between the light source and the converging lens and includes a second opening portion and a cylindrical portion. The second opening portion is configured to restrict a beam path width in a sub scanning direction of the laser beams emitted from the light source, and is formed in the cylindrical portion. The support member includes a cylinder supporting portion that pivotably supports the cylindrical portion of the second aperture.

INCORPORATION BY REFERENCE

This application is based upon and claims the benefit of priority fromthe corresponding Japanese Patent Application No. 2014-111645 filed onMay 29, 2014, the entire contents of which are incorporated herein byreference.

BACKGROUND

The present disclosure relates to an optical scanning device forscanning a laser beam and to an image forming apparatus including theoptical scanning device.

An electrophotographic image forming apparatus includes an opticalscanning device that forms an electrostatic latent image on aphotoconductor by scanning a laser beam over the surface of thephotoconductor. The optical scanning device includes a light source anda polygon mirror, wherein the light source emits a laser beam, and thepolygon mirror scans the laser beam emitted from the light source. Inaddition, in the optical scanning device, an aperture is providedbetween the light source and the polygon mirror, wherein the aperturehas an opening portion that restricts the beam path width of the laserbeam.

Meanwhile, some optical scanning devices may include an adjustmentmechanism for adjusting the fixed state of the aperture. Morespecifically, there is known an adjustment mechanism that can rotate theaperture around the optical axis of the laser beam as the rotation axis,based on the screw-depth of a screw that is screwed into a screw holeprovided in a fixing tool that pivotably supports the aperture. Inaddition, there is known an adjustment mechanism that can move theaperture in a direction perpendicular to the optical axis of the laserbeam, based on the screw-depth of a screw that is screwed into a screwhole provided in a fixing tool that swayably supports the aperture.

SUMMARY

An optical scanning device according to an aspect of the presentdisclosure includes a light source, a scanning member, a converginglens, a first aperture, a second aperture, and a support member. Thelight source is configured to emit a plurality of laser beams. Thescanning member is configured to deflect and scan the laser beamsemitted from the light source. The converging lens is configured toconverge the laser beams emitted from the light source, on a deflectionsurface of the scanning member. The first aperture is provided betweenthe converging lens and the scanning member and includes a first openingportion configured to restrict a beam path width in a main scanningdirection of the laser beams emitted from the light source. The secondaperture is provided between the light source and the converging lensand includes a second opening portion and a cylindrical portion. Thesecond opening portion is configured to restrict a beam path width in asub scanning direction of the laser beams emitted from the light source,and is formed in the cylindrical portion. The support member includes acylinder supporting portion that pivotably supports the cylindricalportion of the second aperture.

An image forming apparatus according to another aspect of the presentdisclosure includes an optical scanning device. The optical scanningdevice includes a light source, a scanning member, a converging lens, afirst aperture, a second aperture, and a support member. The lightsource is configured to emit a plurality of laser beams. The scanningmember is configured to deflect and scan the laser beams emitted fromthe light source. The converging lens is configured to converge thelaser beams emitted from the light source, on a deflection surface ofthe scanning member. The first aperture is provided between theconverging lens and the scanning member and includes a first openingportion configured to restrict a beam path width in a main scanningdirection of the laser beams emitted from the light source. The secondaperture is provided between the light source and the converging lensand includes a second opening portion and a cylindrical portion. Thesecond opening portion is configured to restrict a beam path width in asub scanning direction of the laser beams emitted from the light source,and is formed in the cylindrical portion. The support member includes acylinder supporting portion that pivotably supports the cylindricalportion of the second aperture.

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription with reference where appropriate to the accompanyingdrawings. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter. Furthermore,the claimed subject matter is not limited to implementations that solveany or all disadvantages noted in any part of this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing the configuration of an image formingapparatus according to the first embodiment of the present disclosure.

FIG. 2 is a diagram showing the configuration of an optical scanningdevice according to the first embodiment of the present disclosure.

FIG. 3 is a diagram showing the configuration of a light source unit ofthe optical scanning device according to the first embodiment of thepresent disclosure.

FIG. 4 is a diagram showing the configuration of an outgoing opticalsystem of the optical scanning device according to the first embodimentof the present disclosure.

FIG. 5 is a diagram showing components of the outgoing optical system ofthe optical scanning device according to the first embodiment of thepresent disclosure.

FIG. 6 is a diagram showing components of the outgoing optical system ofthe optical scanning device according to the first embodiment of thepresent disclosure.

FIG. 7 is a diagram for explaining the function of an adjustmentmechanism of the optical scanning device according to the firstembodiment of the present disclosure.

FIGS. 8A-8C are diagrams for explaining the function of the adjustmentmechanism of the optical scanning device according to the firstembodiment of the present disclosure.

FIG. 9 is a flowchart for explaining an aperture fixing method used inthe optical scanning device according to the first embodiment of thepresent disclosure.

FIGS. 10A-10C are diagrams showing examples of photographed images takenby a camera used for the aperture fixing method in the optical scanningdevice according to the first embodiment of the present disclosure.

FIG. 11 is a diagram showing the configuration of an outgoing opticalsystem of an optical scanning device according to the second embodimentof the present disclosure.

FIG. 12 is a diagram showing the configuration of the outgoing opticalsystem of the optical scanning device according to the second embodimentof the present disclosure.

FIG. 13 is a diagram showing the configuration of a light source unit ofan optical scanning device according to the third embodiment of thepresent disclosure.

FIGS. 14A-14B are cross-section schematic diagrams in the main scanningdirection showing examples of trajectories of laser beams in the opticalscanning device according to the third embodiment of the presentdisclosure.

FIG. 15 is a diagram showing the configuration of an outgoing opticalsystem of the optical scanning device according to the third embodimentof the present disclosure.

FIG. 16 is a diagram showing components of the outgoing optical systemof the optical scanning device according to the third embodiment of thepresent disclosure.

FIG. 17 is a diagram showing components of the outgoing optical systemof the optical scanning device according to the third embodiment of thepresent disclosure.

FIG. 18 is a diagram for explaining the function of an adjustmentmechanism of the optical scanning device according to the thirdembodiment of the present disclosure.

FIGS. 19A-19C are diagrams for explaining the function of the adjustmentmechanism of the optical scanning device according to the thirdembodiment of the present disclosure.

FIG. 20 is a diagram showing components of the optical scanning deviceaccording to the third embodiment of the present disclosure.

FIG. 21 is a diagram showing components of the optical scanning deviceaccording to the third embodiment of the present disclosure.

FIG. 22 is a diagram showing components of the optical scanning deviceaccording to the third embodiment of the present disclosure.

FIG. 23 is a diagram for explaining the function of the adjustmentmechanism of the optical scanning device according to the thirdembodiment of the present disclosure.

FIG. 24 is a flowchart for explaining an aperture fixing method used inthe optical scanning device according to the third embodiment of thepresent disclosure.

FIGS. 25A-25D are diagrams showing examples of photographed images takenby a camera used for the aperture fixing method in the optical scanningdevice according to the third embodiment of the present disclosure.

FIG. 26 is a diagram showing a main part of an optical scanning deviceaccording to the fourth embodiment of the present disclosure.

FIG. 27 is a diagram showing the main part of the optical scanningdevice according to the fourth embodiment of the present disclosure.

FIG. 28 is a diagram showing an outgoing optical system of the opticalscanning device according to the fourth embodiment of the presentdisclosure.

FIG. 29 is a diagram showing the outgoing optical system of the opticalscanning device according to the fourth embodiment of the presentdisclosure.

DETAILED DESCRIPTION First Embodiment

The following describes embodiments of the present disclosure withreference to the drawings, for the understanding of the disclosure. Itis noted that embodiments described in the following are merely concreteexamples of the present disclosure, and are not intended to limit thetechnical scope of the present disclosure.

[Outlined Configuration of Image Forming Apparatus 10]

First, an outlined configuration of an image forming apparatus 10 in anembodiment of the present disclosure is described.

As shown in FIG. 1, the image forming apparatus 10 is a color printerincluding a plurality of image forming units 1-4, an intermediatetransfer belt 5, an optical scanning device 6, a secondary transferroller 7, a fixing device 8, a sheet discharge tray 9, a sheet feedcassette 21, and a conveyance path 22. The image forming apparatus 10forms a monochrome image or a color image on a sheet based on inputimage data. It is noted that the sheet is a sheet-like material such asa sheet of paper, a sheet of coated paper, a postcard, an envelope, oran OHP sheet. In addition, other examples of the image forming apparatusof the present disclosure include a facsimile, a copier, and amultifunction peripheral.

The image forming units 1-4 are electrophotographic image forming unitseach including a photoconductor drum, a charging device, a developingdevice, a primary transfer roller, and a cleaning device. The imageforming units 1-4 are arranged in an alignment along the runningdirection (horizontal direction) of the intermediate transfer belt 5,and form an image forming portion of a so-called tandem method.Specifically, the image forming unit 1 forms a toner image correspondingto C (cyan), the image forming unit 2 forms a toner image correspondingto M (magenta), the image forming unit 3 forms a toner imagecorresponding to Y (yellow), and the image forming unit 4 forms a tonerimage corresponding to K (black).

The intermediate transfer belt 5 is an intermediate transfer member onwhich the toner images of the respective colors are intermediatelytransferred from the photoconductor drums of the image forming units1-4. The optical scanning device 6 forms electrostatic latent images onthe photoconductor drums of the image forming units 1-4, by irradiatinglaser beams onto the photoconductor drums based on the input image dataof the respective colors.

In the image forming apparatus 10 configured as such, a color image isformed in the following procedure on a sheet supplied from the sheetfeed cassette 21 along the conveyance path 22, and the sheet with theimage formed thereon is discharged onto the sheet discharge tray 9. Itis noted that various types of conveyance rollers are provided in theconveyance path 22 in such a way as to convey a sheet stacked on thesheet feed cassette 21 to the sheet discharge tray 9 via the secondarytransfer roller 7 and the fixing device 8.

First, in the image forming units 1-4, the charging devices charge thesurfaces of the photoconductor drums uniformly to a certain potential.Next, the optical scanning devices 6 irradiate the surfaces of thephotoconductor drums with laser beams based on the image data. With thisoperation, electrostatic latent images are formed on the surfaces of thephotoconductor drums. The electrostatic latent images on thephotoconductor drums are developed (visualized) as toner images ofrespective colors by the developing devices. It is noted that toners(developers) are supplied from toner containers 11-14 of respectivecolors that are configured to be attachable/detachable.

Subsequently, the toner images of respective colors formed on thephotoconductor drums of the image forming units 1-4 are transferred bythe primary transfer rollers in sequence onto the intermediate transferbelt 5 so as to be overlaid thereon. With this operation, a color imageis formed on the intermediate transfer belt 5 based on the image data.Next, the color image on the intermediate transfer belt 5 is transferredby the secondary transfer roller 7 onto the sheet that has been conveyedfrom the sheet feed cassette 21 via the conveyance path 22.Subsequently, the color image transferred on the sheet is heated by thefixing device 8 so as to be fused and fixed onto the sheet. It is notedthat the toner that has remained on the surfaces of the photoconductordrums is removed by the cleaning devices.

In addition, the image forming apparatus 10 includes acontact/separation mechanism (not shown) that causes the photoconductordrums and the first transfer rollers of the image forming units 1-3 tocontact and separate from the intermediate transfer belt 5. When amonochrome image is printed in the image forming apparatus 10, thecontact/separation mechanism causes the photoconductor drums and thefirst transfer rollers of the image forming units 1-3 to separate fromthe intermediate transfer belt 5. With this operation, only a blacktoner image is transferred from the image forming unit 4 to theintermediate transfer belt 5, and a monochrome image is transferred fromthe intermediate transfer belt 5 to the sheet.

[Configuration of Optical Scanning Device 6]

Next, details of the optical scanning device 6 are described withreference to FIGS. 2-8.

As shown in FIG. 2, the optical scanning device 6 includes a unithousing 60, a light source unit 61, a polygon mirror (an example of thescanning member) 62, and outgoing mirrors 63-66. In the optical scanningdevice 6, laser beams respectively corresponding to the image formingunits 1-4 are emitted from the light source unit 61 and are deflectedand scanned in a main scanning direction D1 by the polygon mirror 62.The laser beams scanned by the polygon mirror 62 are guided to theoutgoing mirrors 63-66 via optical elements such as various types oflenses or mirrors. Subsequently, the laser beams reflected on theoutgoing mirrors 63-66 are irradiated onto the photoconductor drums ofthe image forming units 1-4. It is noted that a direction perpendicularto the main scanning direction D1 on the surface of each photoconductordrum and a direction perpendicular to the main scanning direction D1 onthe surface of the polygon mirror 62 are both referred to as a subscanning direction D2.

Here, as shown in FIG. 3, the light source unit 61 includes LD boards611-614, outgoing optical systems 615-618, reflection mirrors 71-76, anda cylindrical lens 77. The LD boards 611-614 are boards on which laserdiodes 611A-614A are mounted as the light sources that emit laser beamsthat respectively correspond to the photoconductor drums. The outgoingoptical systems 615-618 emit, as parallel luminous fluxes, the laserbeams emitted from the laser diodes 611A-614A respectively, and restrictthe beam path widths of the laser beams.

It is noted that the laser diodes 611A-614A each may be a single-beamlaser diode which emits a single laser beam, or may be a monolithicmulti-beam laser diode which emits a plurality of laser beams. It isnoted that when the laser diodes 611A-614A are monolithic multi-beamlaser diodes, the optical scanning device 6 can write electrostaticlatent images on the photoconductor drums by using a plurality of linessimultaneously.

The reflection mirrors 71-74 reflect, toward the reflection mirror 75,laser beams emitted from the outgoing optical systems 615-618. Thereflection mirror 75 reflects the laser beams toward the reflectionmirror 76, and the reflection mirror 76 reflects the laser beams towardthe cylindrical lens 77. The cylindrical lens 77 is an example of aconverging lens that forms a linear image on the reflection surface(deflection surface) of the polygon mirror 62 by converging the laserbeams in the sub scanning direction D2. Here, the laser beams areincident on the cylindrical lens 77 at different positions along the subscanning direction D2 and incident on the polygon mirror 62 at differentangles. With this configuration, the laser beams reflected on thepolygon mirror 62 are guided to the outgoing mirrors 63-66 separately,and then guided to the photoconductor drums of the image forming units1-4. In this way, in the optical scanning device 6, the cylindrical lens77 and the polygon mirror 62 are used in common to scan the plurality oflaser beams.

In the optical scanning device 6, the outgoing optical systems 615-618include an adjustment mechanism which can adjust the incident positionof a laser beam in the main scanning direction D1 on the polygon mirror62, the incident angle of the laser beam in the sub scanning directionD2, and the inclination around the optical axis of the laser beam. Theadjustment mechanism adjusts the incident position of a laser beam inthe main scanning direction D1 on the polygon mirror 62, the incidentangle of the laser beam in the sub scanning direction D2, and theinclination around the optical axis of the laser beam. Here, when theadjustment mechanism is configured to be able to adjust the fixed stateof an aperture 82 by changing the screw-depth of a screw, the screw maybe loosened due to, for example, vibrations that occur during thetransportation or operation of the image forming apparatus 10, resultingin a change of the fixed state of the aperture 82. On the other hand,the image forming apparatus 10 can adjust the fixed state of theaperture 82 without using a screw. This characteristic is described inthe following in detail.

FIG. 4 is a schematic diagram showing a simplified configuration of theoutgoing optical system 618. In the following, the front-rear,left-right, and up-down directions defined on FIGS. 4-8 may be used forthe sake of explanation. It is noted that although the configuration ofthe adjustment mechanism is described by taking the outgoing opticalsystem 618 as an example, a similar adjustment mechanism is provided ineach of the outgoing optical systems 615-617. That is, the opticalscanning device 6 includes a plurality of sets of the aperture 82, asupport member 84, and a pass-through portion 744 that constitute theadjustment mechanism as described below, in correspondence with thelaser diodes 611A-614A respectively.

The outgoing optical system 618 includes a base portion 681, a wallportion 682, a collimator lens 81, an aperture 82, and a support member84. The base portion 681 and the wall portion 682 constitute a part ofthe unit housing 60. The wall portion 682 has a pass-through portion 743in which the laser diode 614A mounted on the LD board 614 can beinserted.

The base portion 681 includes the pass-through portion 744 that passesthrough between a front surface 681A and a rear surface 681B of the baseportion 681, wherein the support member 84 can be inserted in thepass-through portion 744. In the state where the support member 84 isinserted in the pass-through portion 744, the support member 84 is fixedto the base portion 681 by adhesion fixing using adhesive. It is notedthat the base portion 681 is an example of the first base portion, andthe pass-through portion 744 is an example of the first pass-throughportion.

The collimator lens 81 is fixed to the base portion 681 by adhesionfixing using adhesive. The collimator lens 81 causes the laser beamemitted from the laser diode 614A of the LD board 614, to become aparallel luminous flux, and emits the parallel luminous flux. Theaperture 82 includes an opening portion 83 that restricts, to a width ina predetermined range, the beam path width in the main scanningdirection D1 and the sub scanning direction D2 of the laser beam whichis traveling from the collimator lens 81 to the reflection mirror 74. Itis noted that the aperture 82 is an example of the first aperture, andthe opening portion 83 is an example of the first opening portion. Thesupport member 84 supports the aperture 82, and is configured as adifferent member from the base portion 681.

FIG. 5 is a diagram showing the configuration of the aperture 82 and thesupport member 84. As shown in FIG. 5, the aperture 82 includes anoperation portion 821 and a cylindrical portion 822. The cylindricalportion 822 is formed in the shape of a cylinder whose axis is thecenter of the opening portion 83. The opening portion 83 of the aperture82 is formed to pass through between a top surface and a bottom surfaceof the cylindrical portion 822. The operation portion 821 is formed toproject from the circumferential surface of the cylindrical portion 822in a direction perpendicular to the longitudinal direction of theopening portion 83. Furthermore, the operation portion 821 has such alength that the upper end thereof projects upward from the supportmember 84 in the state where the aperture 82 is supported by the supportmember 84.

The support member 84 includes a cylinder supporting portion 841, a cutportion 842, and groove portions 843. The cylinder supporting portion841 is formed to extend between a front surface and a rear surface ofthe support member 84, and pivotably supports the cylindrical portion822 of the aperture 82. The cut portion 842 is formed in an upper endportion 84A of the support member 84 to avoid an interruption with theoperation portion 821 of the aperture 82 when the cylindrical portion822 of the aperture 82 is inserted into the cylinder supporting portion841.

Here, the support member 84 has such a length that a lower end portion84B thereof projects from a rear surface 681B of the base portion 681 inthe state where the support member 84 has been inserted in thepass-through portion 744 to such a position where the laser beam isincident in the opening portion 83 of the aperture 82. In particular,the distance between the lower end portion 84B and a lower end positionof the cylinder supporting portion 841 of the support member 84 isdesigned to be larger than the thickness of the base portion 681 by apredetermined adjustment width. In addition, the groove portions 843 areformed to extend in the up-down direction that is the longitudinaldirection of the support member 84, respectively on the left sidesurface and the right side surface of the support member 84.

Here, FIG. 6 is a diagram showing the configuration of the base portion681. As shown in FIG. 6, the pass-through portion 744 formed in the baseportion 681 includes restriction portions 745 that are projectionsrespectively projecting from the left and right end portions toward theinside of the pass-through portion 744, wherein the restriction portions745 are configured to be inserted in the groove portions 843 of thesupport member 84. The restriction portions 745 are formed to extendbetween the front surface and the rear surface of the base portion 681.In addition, the restriction portions 745, when inserted in the grooveportions 843 of the support member 84, restrict the movement of thesupport member 84 in the front-rear direction, which is a directionalong the pivoting axis of the aperture 82. On the other hand, in thepass-through portion 744, the movement of the support member 84 in theup-down direction and the left-right direction (the main scanningdirection D1 and the sub scanning direction D2) that are perpendicularto the pivoting axis of the aperture 82 is allowed within apredetermined adjustment range.

In the outgoing optical system 618 which is configured as describedabove, after the support member 84 is inserted in the pass-throughportion 744 of the base portion 681, it is possible to adjust theposition of the aperture 82 in the up, down, left and right directionsand the rotation position of the aperture 82 around the optical axis ofthe laser beam that is incident in the aperture 82.

Here, FIG. 7 is a schematic diagram, viewed from above, showing thestate where the support member 84 is inserted in the pass-throughportion 744 of the base portion 681. As shown in FIG. 7, in the statewhere the support member 84 is inserted in the pass-through portion 744,a gap with a predetermined adjustment width w1 is formed in each of theleft and right groove portions 843, wherein the adjustment width w1 isset with respect to the restriction portions 745 in advance and extendsin the left-right direction. That is, in this state, the support member84 can be moved in the main scanning direction D1 in the pass-throughportion 744 within a width range that is twice as large as theadjustment width w1. With this configuration, when the optical scanningdevice 6 is assembled, it is possible to adjust the incident position ofthe laser beam in the main scanning direction D1 on the polygon mirror62.

Furthermore, the support member 84 can be moved in the up-down directionalong the restriction portions 745 in the state where the restrictionportions 745 are inserted in the groove portions 843. With thisconfiguration, when the optical scanning device 6 is assembled, it ispossible to change the incident position of the laser beam on thecylindrical lens 77, and adjust the incident angle of the laser beam inthe sub scanning direction D2 on the polygon mirror 62.

In the outgoing optical system 618, after the position of the supportmember 84 in the pass-through portion 744 in the up-down direction andleft-right direction is adjusted, the support member 84 is fixed to thebase portion 681 by adhesion fixing using adhesive. At this time, forexample, a photocurable resin that is cured by ultraviolet irradiationis used as the adhesive. In that case, it is necessary to irradiateultraviolet light on the photocurable resin after the photocurable resinis applied to the support member 84 and the pass-through portion 744.Here, if the support member 84 could be held only by the upper endportion 84A of the support member 84, the chuck portion of the robot armor the hand of the worker that would be holding the support member 84would interrupt with the application of the photocurable resin and theirradiation of the ultraviolet light on the photocurable resin.

In the outgoing optical system 618, however, the lower end portion 84Bof the support member 84 projects from the rear surface 681B of the baseportion 681 in the state where the support member 84 has been insertedin the pass-through portion 744 to such a position where the laser beamis incident in the opening portion 83 of the aperture 82. As a result,it is possible to apply the photocurable resin to the support member 84and the pass-through portion 744 and irradiate the ultraviolet light onthe photocurable resin from above in the state where the chuck portionof the robot arm or the hand of the worker is holding the lower endportion 84B of the support member 84 on the rear surface 681B side ofthe base portion 681. It is noted that the photocurable resin may beapplied to the support member 84 and the pass-through portion 744 fromthe rear surface 681B side of the base portion 681 and the ultravioletlight may be irradiated on the photocurable resin from the rear surface681B side of the base portion 681 in the state where the upper endportion 84A of the support member 84 is held.

FIGS. 8A-8C are front views showing the state where the support member84 is inserted in the pass-through portion 744 of the base portion 681.In the support member 84, as shown in FIG. 8A, the cylindrical portion822 of the aperture 82 is pivotably supported by the cylinder supportingportion 841. In addition, as shown in FIGS. 8B and 8C, when theoperation portion 821 is moved in the left-right direction, the aperture82 pivots around the center of the opening of the cylinder supportingportion 841 and the center of the cylindrical portion 822 as thepivoting axis. With this configuration, when the optical scanning device6 is assembled, it is possible to adjust the inclination around theoptical axis of the laser beam on the polygon mirror 62. It is notedthat the inclination around the optical axis of the laser beam occurs,for example, due to an installation error of various types of mirrorsthat are disposed in the light source unit 61.

As described above, the optical scanning device 6 includes an adjustmentmechanism that can adjust the incident position of a laser beam in themain scanning direction D1 on the polygon mirror 62, the incident angleof the laser beam in the sub scanning direction D2, and the inclinationaround the optical axis of the laser beam, by adjusting the fixed stateof the aperture 82. In addition, the adjustment mechanism has a simpleconfiguration where a screw or the like is not used. This makes itpossible to reduce the number of parts and the cost. Furthermore, theconfiguration facilitates the work of fixing the support member 84 tothe base portion 681 by adhesion fixing. As a result, it is possible tofix the aperture 82 stably in a desired fixed state by using adhesivesuch as photocurable resin.

[Aperture Fixing Method in Optical Scanning Device 6 of FirstEmbodiment]

Here, with reference to FIG. 9, a description is given of the workprocess executed as a fixing method of the aperture 82 in the opticalscanning device 6. The work process is executed by, for example, a robotarm or a worker who performs the assembling of the optical scanningdevice 6.

First, in step S1, the position of the support member 84 in the up-downdirection and the left-right direction (the main scanning direction D1and the sub scanning direction D2) that are perpendicular to thepivoting axis of the aperture 82 is adjusted by moving the supportmember 84 in the pass-through portion 744 of the base portion 681.

Next, in step S2, the support member 84 whose position has been adjustedin the step S2 is fixed to the base portion 681 by adhesion fixing usingadhesive. Here, a photocurable resin that is cured by ultravioletirradiation is used as the adhesive. More specifically, the photocurableresin is applied to between the support member 84 and the pass-throughportion 744, and then ultraviolet light is irradiated on thephotocurable resin. At this time, since the lower end portion 84B of thesupport member 84 projects from the bottom surface of the base portion681, it is possible to perform with ease the application of thephotocurable resin and the irradiation of ultraviolet light on thephotocurable resin from above the base portion 681, in the state wherethe lower end portion 84B of the support member 84 is held.

Subsequently, in step S3, the rotation position of the aperture 82 isadjusted by pivoting the aperture 82 by operating the operation portion821 of the aperture 82 supported by the support member 84 fixed to thebase portion 681.

In step S4, the aperture 82 whose rotation position has been adjusted inthe step S3 is fixed to the support member 84 by adhesion fixing usingadhesive. In this case, too, a photocurable resin that is cured byultraviolet irradiation is used as the adhesive. More specifically, thephotocurable resin is applied to between the cylindrical portion 822 ofthe aperture 82 and the cut portion 842 of the support member 84, andthen ultraviolet light is irradiated on the photocurable resin. At thistime, since the operation portion 821 of the aperture 82 projects upwardfrom the cylindrical portion 822, it is possible to perform with easethe application of the photocurable resin to the cut portion 842 and theirradiation of ultraviolet light on the photocurable resin in the statewhere the operation portion 821 of the aperture 82 is held.

Second Embodiment

Meanwhile, the adjustment of the fixed state of the aperture 82 may beperformed while photographing the laser beam by a camera including animaging element such as CCD. For example, during the adjustment work,the camera may be disposed between the reflection mirrors 71-74 and thereflection mirror 75, or between the cylindrical lens 77 and the polygonmirror 62, and after the adjustment work, the camera may be removed.

However, when, for example, the focal distance of a scanning lens suchas an Fθ lens mounted in the optical scanning device 6 is long, the beamwidth in the main scanning direction D1 increases after the laser beampasses through the aperture 82. When the size of the camera is smallrelative to the beam width in the main scanning direction D1 of thelaser beam, the end portions of the laser beam in the main scanningdirection D1 may not be included in a photographed image P1 taken by thecamera, as shown in FIG. 10A. It is noted that, as shown in FIGS.10A-10C, the camera is disposed in the optical scanning device 6 suchthat the left-right direction of the photographed image P1 is parallelto the main scanning direction D1 and the up-down direction is parallelto the sub scanning direction D2. It is noted that, in FIGS. 10A-10C,the laser beam is represented by the hatched area.

Here, it may be considered to use a large-size camera to photograph thelaser beam in its entirety in the main scanning direction D1. However,in that case, the setting position of the camera in the optical scanningdevice 6 is restricted when the fixed state of the aperture 82 isadjusted.

On the other hand, the image forming apparatus 10 according to thesecond embodiment described herewith provides a configuration where asmall-size camera can be used when the fixed state of the aperture 82 isadjusted. It is noted that the components that are the same as those ofthe image forming apparatus 10 and the optical scanning device 6described in the first embodiment are assigned the same reference signs,and description thereof is omitted.

Specifically, in the image forming apparatus 10 according to the secondembodiment, as shown in FIG. 11, the aperture 82 includes a cut portion97 in which a blocking member 98 that is described below can be insertedin a direction perpendicular to the longitudinal direction of theopening portion 83. Here, the cut portion 97 is an example of the firstcut portion, and the blocking member 98 is an example of the firstblocking member. The cut portion 97 is formed at a predeterminedposition such that the center thereof in the main scanning direction D1matches the center of the opening portion 83 in the main scanningdirection D1. The cut portion 97 is an indent portion formed on thesurface (namely, the front surface) of the aperture 82 on the downstreamside in the emission direction of the laser beam, and does not passthrough the aperture 82 in a direction along the optical axis of thelaser beam. As a result, the cut portion 97 does not affect theperformance of the opening portion 83 of the aperture 82 in restrictingthe width of the laser beam.

As shown in FIG. 12, the blocking member 98 which is in the shape of along cylinder can be attached to and detached from the cut portion 97,wherein the blocking member 98 blocks the laser beam emitted from thelaser diode 614A. When a photograph is taken by the camera in the statewhere the blocking member 98 is attached to the cut portion 97, in thephotographed image P1, a part of the laser beam emitted from the laserdiode 614A is blocked by the blocking member 98, as shown in FIG. 10B.At this time, a blocked area A1 that is formed in the laser beam by theblocking member 98 has a predetermined relationship with the openingportion 83 of the aperture 82. That is, the center of the openingportion 83 in the longitudinal direction thereof matches the center ofthe blocked area A1 in the same direction. It is noted that a borderline between the blocked area A1 and the laser beam forms a line segmentthat is perpendicular to the longitudinal direction of the openingportion 83.

With the above-described configuration, it is possible to identify thecenter position in the main scanning direction D1 of the laser beamemitted from the opening portion 83 of the aperture 82, by referring tothe blocked area A1 in the photographed image P1. More specifically, thecenter position of the laser beam is where the center of a width w2passes through the center between the border lines of the blocked areaA1 with the laser beam, wherein the width w2 extends in a directionperpendicular to the border lines. As a result, even when one or bothends of the laser beam are not included in the photographed image takenby the camera as shown in FIG. 10B, it is possible to identify thecenter position of the laser beam by referring to the blocked area A1.Furthermore, in the optical scanning device 6, it is possible, by usingthe adjustment mechanism, to adjust with ease the fixed position of theaperture 82 in the main scanning direction D1 (the left-rightdirection).

In addition, in the photographed image P1, the blocked area A1 generatedby the blocking member 98 is inclined when the laser beam that isemitted from the aperture 82 and enters the camera is inclined aroundthe pivoting axis of the aperture 82, as shown in FIG. 10C. As a result,it is possible to identify the inclinatin of the laser beam by referringto the blocked area A1 in the photographed image P1. More specifically,the inclination of a line segment matches the inclination of the laserbeam, wherein the line segment passes through the center between theborder lines of the blocked area A1 with the laser beam, and isperpendicular to the border lines. As a result, even when one or bothends of the laser beam are not included in the photographed image takenby the camera as shown in FIG. 10C, it is possible, by referring to theblocked area A1, to identify the inclination of the laser beam. Inaddition, it is possible to adjust with ease the rotation position ofthe aperture 82 rotated around the pivoting axis of the aperture 82.

As described above, according to the optical scanning device 6 of thesecond embodiment, it is possible to use a small-size camera when thefixed state of the aperture 82 is adjusted, resulting in relaxation ofthe restriction made to the setting position of the camera in theoptical scanning device 6.

More specifically, in the optical scanning device 6 of the secondembodiment, the following work process is executed in the step S1 of thework process executed as the fixing method of the aperture 82. First,the laser beam after passing through the opening portion 83 isphotographed by a camera installed at a predetermined position, in thestate where the blocking member 98 is inserted in the cut portion 97 ofthe aperture 82. Next, the center position of the laser beam in thelongitudinal direction (the main scanning direction D1) of the openingportion 83 after passing through the opening portion 83, is identifiedbased on the photographed image taken by the camera. Subsequently, thefixed state of the support member 84 is adjusted based on the identifiedcenter position of the laser beam in the longitudinal direction of theopening portion 83. In addition, the rotation position of the aperture82 in the support member 84 is adjusted based on the photographed imagetaken by the camera.

Third Embodiment

Meanwhile, according to the above description of the first embodimentand the second embodiment, one aperture 82 is used to restrict the widthof the laser beam in the main scanning direction D1 and the sub scanningdirection D2. In the third embodiment provided herewith, a descriptionis given of a configuration where the beam path widths of the laser beamin the main scanning direction D1 and the sub scanning direction D2 arerestricted by individual apertures. It is noted that the components thatare the same as those of the image forming apparatus 10 and the opticalscanning device 6 described in the first embodiment are assigned thesame reference signs, and description thereof is omitted.

Specifically, as shown in FIG. 13, the laser diodes 611A-614A providedin the optical scanning device 6 of the third embodiment are monolithicmulti-beam laser diodes that can emit two laser beams. When the laserdiodes 611A-614A are the monolithic multi-beam laser diodes, the opticalscanning device 6 can write electrostatic latent images on thephotoconductor drums by using two lines simultaneously. It is noted thatthe laser diodes 611A-614A may be configured to emit three or more laserbeams.

The optical scanning device 6 of the third embodiment includes apertures91 and an aperture 92 in place of the apertures 82. The apertures 91 areprovided in correspondence with the laser diodes 611A-614A respectively.

Each aperture 91 restricts the beam path width of the laser beam in thesub scanning direction D2 that is emitted from a corresponding one ofthe laser diodes 611A-614A. In addition, the aperture 92 restricts thebeam path width in the main scanning direction D1 of the laser beamsemitted from the laser diodes 611A-614A. That is, the aperture 92 is asingle aperture that is common to the laser diodes 611A-614A. Eachaperture 91 is disposed between the collimator lens 81 and thecylindrical lens 77 on a base portion 683 that constitutes a part of theunit housing 60. On the other hand, the aperture 92 is disposed betweenthe cylindrical lens 77 and the polygon mirror 62 on a base portion 686that constitutes a part of the unit housing 60.

FIG. 14A is a cross-section schematic diagram in the main scanningdirection D1 showing trajectories of laser beams in the optical scanningdevice 6. It is noted that in FIG. 14A, the reflection mirrors 71-76 areomitted. As shown in FIG. 14A, two laser beams L1 and L2 emitted fromthe laser diode 614A have respective beam emitting points that aredifferent in position in the main scanning direction D1 and the subscanning direction D2.

The laser beam L1 and the laser beam L2 pass through the collimator lens81 and then the aperture 91, and enter the cylindrical lens 77.Subsequently, the laser beam L1 and the laser beam L2 emitted from thecylindrical lens 77 pass through the aperture 92 and enter the polygonmirror 62. The laser beam L1 and the laser beam L2 are then deflectedand scanned by the polygon mirror 62, passed through a scanning lens 67such as an f0 lens and irradiated on the surface of the photoconductordrum. It is noted that the laser beam L1 and the laser beam L2 shown inFIG. 14A indicate trajectories of components of the laser beam Li andthe laser beam L2 that pass through the optical axis center of theaperture 92.

As described above, in the optical scanning device 6, the apertures 91are disposed between the collimator lenses 81 and the cylindrical lens77, and the aperture 92 is disposed between the cylindrical lens 77 andthe polygon mirror 62. As a result, it is possible to set the positionof the aperture 92 close to the polygon mirror 62 while ensuring thefocal distance of the cylindrical lens 77. It is thus possible to narrowa pitch d1 between the laser beam L1 and the laser beam L2 on thepolygon mirror 62. With this configuration of the optical scanningdevice 6 of the third embodiment, it is possible to reduce the size ofthe polygon mirror 62, and reduce the size of the optical scanningdevice 6.

On the other hand, FIG. 14B is a cross-section schematic diagram in themain scanning direction D1 showing trajectories of laser beams in theoptical scanning device 6 in an imaginary case where each aperture 91and the aperture 92 are disposed between the collimator lens 81 and thecylindrical lens 77. It is noted that the laser beam L1 and the laserbeam L2 shown in FIG. 14B, as in FIG. 14A, indicate trajectories ofcomponents of the laser beam L1 and the laser beam L2 that pass throughthe optical axis center of the aperture 92. In the example shown in FIG.14B, the laser beams L1 and L2, after passing through the aperture 92,spread in the main scanning direction D1, and thus a pitch d2 betweenthe laser beam L1 and the laser beam L2 on the polygon mirror 62 iswider than the pitch d1. As a result, the polygon mirror 62 needs to beincreased in size, resulting in inhibition of the size reduction.

Next, the configuration of the apertures 91 and the aperture 92 isdescribed with reference to FIGS. 15-22.

As shown in FIG. 15, the outgoing optical system 618 includes a baseportion 683, the wall portion 682, the collimator lens 81, the aperture91, and a support member 93. In the optical scanning device 6 of thethird embodiment, the apertures 91, the support member 93, and apass-through portion 684 that is described below are included in aplurality of sets of structural elements of the adjustment mechanismthat are provided in correspondence with the outgoing optical systems615-618.

The support member 93 is configured to support the apertures 91, and isprovided as a different member from the base portion 683. The baseportion 683 includes the pass-through portion 684 that passes throughbetween a front surface 683A and a rear surface 683B of the base portion683, wherein the support member 93 can be inserted in the pass-throughportion 684. The support member 93 is fixed to the base portion 683 byadhesion fixing using adhesive in the state where the support member 93is inserted in the pass-through portion 684. It is noted that the baseportion 683 is an example of the second base portion.

Each aperture 91 includes an opening portion 911 configured to restrictthe beam path width of the laser beam in the sub scanning direction D2to a width in a predetermined range, the laser beam traveling from thecollimator lens 81 to the reflection mirror 74. Specifically, theopening portion 911 has predetermined widths respectively in the mainscanning direction D1 and the sub scanning direction D2, and the widthin the sub scanning direction D2 is smaller than that of an openingportion 921 included in the aperture 92, wherein the opening portion 921is described below. Here, the apertures 91 are an example of the secondaperture, and the opening portion 911 is an example of the secondopening portion.

FIG. 16 is a diagram showing the configurations of the aperture 91 andthe support member 93. As shown in FIG. 16, the aperture 91 includes anoperation portion 912 and a cylindrical portion 913. The cylindricalportion 913 is formed in the shape of a cylinder whose axis is thecenter of the opening portion 911. The opening portion 911 of theaperture 91 is formed to pass through between a top surface and a bottomsurface of the cylindrical portion 913. The operation portion 912 isformed to project from the circumferential surface of the cylindricalportion 913 in a direction perpendicular to the longitudinal directionof the opening portion 911. Furthermore, the operation portion 912 hassuch a length that the upper end thereof projects upward from thesupport member 93 in the state where the aperture 91 is supported by thesupport member 93.

The support member 93 includes a cylinder supporting portion 931, a cutportion 932, and groove portions 933. The cylinder supporting portion931 is formed to extend between a front surface and a rear surface ofthe support member 93, and pivotably supports the cylindrical portion913 of the aperture 91. The cut portion 932 is formed in an upper endportion 93A of the support member 93 to avoid an interruption with theoperation portion 912 of the aperture 91 when the cylindrical portion913 of the aperture 91 is inserted into the cylinder supporting portion931.

Here, a lower end portion 93B of the support member 93 has a length suchthat the lower end portion 93B projects from a rear surface 683B of thebase portion 683 in the state where the support member 93 has beeninserted in the pass-through portion 684 to such a position where thelaser beam is incident in the opening portion 911 of the aperture 91. Inparticular, the distance between the lower end portion 93B and a lowerend position of the cylinder supporting portion 931 of the supportmember 93 is designed to be larger than the thickness of the baseportion 683 by a predetermined adjustment width. In addition, the grooveportions 933 are formed to extend in the up-down direction that is thelongitudinal direction of the support member 93, respectively on theleft side surface and the right side surface of the support member 93.

Here, FIG. 17 is a diagram showing the configuration of the base portion683. As shown in FIG. 17, the pass-through portion 684 of the baseportion 683 includes restriction portions 685 that are projectionsrespectively projecting from the left and right end portions toward theinside of the pass-through portion 684, and can be inserted in thegroove portions 933 of the support member 93. The restriction portions685 are formed to extend between the front surface and the rear surfaceof the base portion 683. In addition, the restriction portions 685, wheninserted in the groove portions 933 of the support member 93, restrictthe movement of the support member 93 in the front-rear direction, whichis a direction along the pivoting axis of the aperture 91. On the otherhand, in the pass-through portion 684, the movement of the supportmember 93 in the up-down direction (the sub scanning direction D2) whichis perpendicular to the pivoting axis of the aperture 91 is allowedwithin a predetermined adjustment range. Here, the pass-through portion684 is an example of the second pass-through portion.

In the outgoing optical system 618 which is configured as describedabove, after the support member 93 is inserted in the pass-throughportion 684 of the base portion 683, it is possible to adjust theposition of the aperture 91 in the up-down direction and the rotationposition of the aperture 91 around the optical axis of the laser beamthat is incident in the aperture 91.

Here, FIG. 18 is a schematic diagram, viewed from above, showing thestate where the support member 93 is inserted in the pass-throughportion 684 of the base portion 683. As shown in FIG. 18, in the statewhere the support member 93 is inserted in the pass-through portion 684,the movement of the support member 93 in the left-right direction isrestricted by the groove portions 933 and the restriction portions 685.On the other hand, in the state where the restriction portions 685 areinserted in the groove portions 933, the support member 93 can be movedin the up-down direction along the restriction portions 685. With thisconfiguration, when the optical scanning device 6 is assembled, it ispossible to change the incident position of the laser beam on thecylindrical lens 77, and adjust incident angle of the laser beam in thesub scanning direction D2 on the polygon mirror 62.

In the outgoing optical system 618, after the position of the supportmember 93 in the up-down direction in the pass-through portion 684 isadjusted, the support member 93 is fixed to the base portion 683 byadhesion fixing using adhesive. At this time, for example, aphotocurable resin that is cured by ultraviolet irradiation is used asthe adhesive. In that case, it is necessary to irradiate ultravioletlight on the photocurable resin after the photocurable resin is appliedto the support member 93 and the pass-through portion 684. Here, if thesupport member 93 could be held only by the upper end portion 93A of thesupport member 93, the chuck portion of the robot arm or the hand of theworker that would be holding the support member 93 would interrupt withthe application of the photocurable resin and the irradiation of theultraviolet light on the photocurable resin.

In the outgoing optical system 618, however, the lower end portion 93Bof the support member 93 projects from the rear surface 683B of the baseportion 683 in the state where the support member 93 has been insertedin the pass-through portion 684 to such a position where the laser beamis incident in the opening portion 911 of the aperture 91. As a result,it is possible to apply the photocurable resin to the support member 93and the pass-through portion 684 and irradiate the ultraviolet light onthe photocurable resin from above in the state where the chuck portionof the robot arm or the hand of the worker is holding the lower endportion 93B of the support member 93 on the rear surface 683B side ofthe base portion 683. It is noted that the photocurable resin may beapplied to the support member 93 and the pass-through portion 684 fromthe rear surface 683B side of the base portion 683 and the ultravioletlight may be irradiated on the photocurable resin from the rear surface683B side of the base portion 683 in the state where the upper endportion 93A of the support member 93 is held.

FIGS. 19A-19C are front views showing the state where the support member93 is inserted in the pass-through portion 684 of the base portion 683.In the support member 93, as shown in FIG. 19A, the cylindrical portion913 of the aperture 91 is pivotably supported by the cylinder supportingportion 931. In addition, as shown in FIGS. 19B and 19C, when theoperation portion 912 is moved in the left-right direction, the aperture91 pivots around the center of the opening of the cylinder supportingportion 931 and the center of the cylindrical portion 913 as thepivoting axis. With this configuration, when the optical scanning device6 is assembled, it is possible to adjust the inclination around theoptical axis of the laser beam on the polygon mirror 62. In particular,in the optical scanning device 6 of the third embodiment, theinclination around the optical axis of the laser beam can be adjusted atthe apertures 91, among the apertures 91 and the aperture 92, that areeach disposed between the collimator lens 81 and the cylindrical lens 77and restrict the beam path width in the sub scanning direction D2. As aresult, it is possible to correct the inclination of the laser beambefore the laser beam is incident in the cylindrical lens 77, andcorrect the inclination of the laser beam on the polygon mirror 62. Itis noted that the inclination around the optical axis of the laser beamoccurs, for example, due to an installation error of various types ofmirrors that are disposed in the light source unit 61.

FIGS. 20-22 are diagrams showing the configuration of the aperture 92and the base portion 686. As shown in FIG. 20, the base portion 686includes the pass-through portion 687 that passes through between afront surface 686A and a rear surface 686B of the base portion 686,wherein the aperture 92 can be inserted in the pass-through portion 687.The aperture 92 is fixed to the base portion 686 by adhesion fixingusing adhesive in the state where the aperture 92 is inserted in thepass-through portion 687. It is noted that the base portion 686 is anexample of the first base portion.

In addition, as shown in FIGS. 20 and 21, the aperture 92 includes anopening portion 921, a restriction portion 922, and groove portions 923.The opening portion 921 is formed to extend from the front surface tothe rear surface of the aperture 92. The opening portion 921 isconfigured to restrict the beam path width of the laser beam in the mainscanning direction D1 to a width in a predetermined range, the laserbeam traveling from the cylindrical lens 77 to the polygon mirror 62.Specifically, the opening portion 921 has predetermined widths in themain scanning direction D1 and the sub scanning direction D2, and thewidth in the main scanning direction D1 is smaller than that of theopening portion 911 of the apertures 91. Here, the aperture 92 is anexample of the first aperture, and the opening portion 921 is an exampleof the first opening portion.

The restriction portion 922 is formed to project from the aperture 92 inthe axis direction of the laser beam, and restricts the downwardmovement of the aperture 92 in the pass-through portion 687. It is notedthat the groove portions 923 are formed to extend from the upper end tothe lower end of the aperture 92.

As shown in FIG. 22, the pass-through portion 687 formed in the baseportion 686 includes restriction portions 688 that are projectionsrespectively projecting from the left and right end portions toward theinside of the pass-through portion 687, and can be inserted in thegroove portions 923 of the aperture 92. The restriction portions 688 areformed to extend between the front surface and the rear surface of thebase portion 686. In addition, the restriction portions 688, wheninserted in the groove portions 923 of the aperture 92, restrict themovement of the aperture 92 in the front-rear direction. On the otherhand, in the pass-through portion 687, the movement of the aperture 92in the left-right direction (the main scanning direction D1) that isperpendicular to the pivoting axis of the aperture 92 is allowed withina predetermined adjustment range. Here, the pass-through portion 687 isan example of the first pass-through portion.

In the aperture 92 which is configured as described above, after theaperture 92 is inserted in the pass-through portion 687 of the baseportion 686, it is possible to adjust the position of the aperture 92 inthe left-right direction. Here, FIG. 23 is a schematic diagram, viewedfrom above, showing the state where the aperture 92 is inserted in thepass-through portion 687 of the base portion 686. As shown in FIG. 23,in the state where the aperture 92 is inserted in the pass-throughportion 687, a gap with a predetermined adjustment width w1 is formed ineach of the left and right groove portions 923, wherein the adjustmentwidth w1 is set with respect to the restriction portions 688 in advanceand extends in the left-right direction. That is, in this state, theaperture 92 can be moved in the main scanning direction D1 in thepass-through portion 688 within a width range that is twice as large asthe adjustment width w1. With this configuration, when the opticalscanning device 6 is assembled, it is possible to adjust the incidentposition of the laser beam in the main scanning direction D1 on thepolygon mirror 62.

In the optical scanning device 6, after the position of the aperture 92in the left-right direction in the pass-through portion 687 is adjusted,the aperture 92 is fixed to the base portion 686 by adhesion fixingusing adhesive. At this time, for example, a photocurable resin that iscured by ultraviolet irradiation is used as the adhesive. In that case,it is necessary to irradiate ultraviolet light on the photocurable resinafter the photocurable resin is applied to the aperture 92 and thepass-through portion 687. Here, if the aperture 92 could be held only bythe upper end portion 92A of the aperture 92, the chuck portion of therobot arm or the hand of the worker that would be holding the aperture92 would interrupt with the application of the photocurable resin andthe irradiation of the ultraviolet light on the photocurable resin.

In the optical scanning device 6, however, the lower end portion 92B ofthe aperture 92 projects from the rear surface 686B of the base portion686 in the state where the aperture 92 has been inserted in thepass-through portion 687 to such a position where the laser beam isincident in the opening portion 921 of the aperture 92. As a result, itis possible to apply the photocurable resin to the aperture 92 and thepass-through portion 687 and irradiate the ultraviolet light on thephotocurable resin from above in the state where the chuck portion ofthe robot arm or the hand of the worker is holding the lower end portion92B of the aperture 92 on the rear surface 686B side of the base portion686. It is noted that the photocurable resin may be applied to theaperture 92 and the pass-through portion 687 from the rear surface 686Bside of the base portion 686 and the ultraviolet light may be irradiatedon the photocurable resin from the rear surface 686B side of the baseportion 686 in the state where the upper end portion 92A of the aperture92 is held.

As described above, the optical scanning device 6 according to the thirdembodiment includes an adjustment mechanism that can adjust the incidentposition of a laser beam in the main scanning direction D1 on thepolygon mirror 62, the incident angle of the laser beam in the subscanning direction D2, and the inclination around the optical axis ofthe laser beam. In addition, the adjustment mechanism has a simpleconfiguration where a screw or the like is not used. This makes itpossible to reduce the number of parts and the cost. Furthermore, theconfiguration facilitates the work of fixing the support member 93 andthe aperture 92 to the base portion 683 and the base portion 686 byadhesion fixing. As a result, it is possible to fix the support member93 and the aperture 92 stably in a desired fixed state by using adhesivesuch as photocurable resin.

[Aperture Fixing Method in Optical Scanning Device 6 of ThirdEmbodiment]

Here, with reference to FIG. 24, a description is given of the workprocess executed as a fixing method of the apertures 91 and the aperture92 in the optical scanning device 6 of the third embodiment. The workprocess is executed by, for example, a robot arm or a worker whoperforms the assembling of the optical scanning device 6.

First, in step S11, the position of the aperture 91 in the up-downdirection (the sub scanning direction D2) which is perpendicular to thepivoting axis of the aperture 91 is adjusted by moving the supportmember 93 in the pass-through portion 744 of the base portion 683.

Next, in step S12, the support member 93 whose position has beenadjusted in the step S11 is fixed to the base portion 683 by adhesionfixing using adhesive. Here, a photocurable resin that is cured byultraviolet irradiation is used as the adhesive. More specifically, thephotocurable resin is applied to between the support member 93 and thepass-through portion 744, and then ultraviolet light is irradiated onthe photocurable resin. At this time, since the lower end portion 93B ofthe support member 93 projects from the bottom surface of the baseportion 683, it is possible to perform with ease the application of thephotocurable resin and the irradiation of ultraviolet light on thephotocurable resin from above the base portion 683, in the state wherethe lower end portion 93B of the support member 93 is held.

Subsequently, in step S13, the rotation position of the aperture 91 isadjusted by pivoting the aperture 91 by operating the operation portion912 of the aperture 91 supported by the support member 93 fixed to thebase portion 683.

In step S14, the aperture 91 whose rotation position has been adjustedin the step S13 is fixed to the support member 93 by adhesion fixingusing adhesive. In this case, too, a photocurable resin that is cured byultraviolet irradiation is used as the adhesive. More specifically, thephotocurable resin is applied to between the cylindrical portion 913 ofthe aperture 91 and the cut portion 932 of the support member 93, andthen ultraviolet light is irradiated on the photocurable resin. At thistime, since the operation portion 912 of the aperture 91 projects upwardfrom the cylindrical portion 913, it is possible to perform with easethe application of the photocurable resin to the cut portion 932 and theirradiation of ultraviolet light on the photocurable resin in the statewhere the operation portion 912 of the aperture 91 is held.

Subsequently, in step S15, the position of the aperture 92 in theleft-right direction (the main scanning direction D1), which isperpendicular to the pivoting axis of the aperture 92, is adjusted bymoving the aperture 92 in the pass-through portion 687 of the baseportion 686.

In step S16, the aperture 92 whose position has been adjusted in thestep S15 is fixed to the base portion 686 by adhesion fixing usingadhesive. Here, a photocurable resin that is cured by ultravioletirradiation is used as the adhesive. More specifically, the photocurableresin is applied to between the aperture 92 and the pass-through portion687, and then ultraviolet light is irradiated on the photocurable resin.At this time, since the lower end portion 92B of the aperture 92projects from the bottom surface of the base portion 686, it is possibleto perform with ease the application of the photocurable resin and theirradiation of ultraviolet light on the photocurable resin from abovethe base portion 686, in the state where the lower end portion 92B ofthe aperture 92 is held.

Fourth Embodiment

Meanwhile, the adjustment of the fixed state of the apertures 91 and theaperture 92 may be performed while photographing the laser beam by acamera including an imaging element such as CCD. For example, during theadjustment work, the camera may be disposed between the reflectionmirrors 71-74 and the reflection mirror 75, or between the cylindricallens 77 and the polygon mirror 62, and after the adjustment work, thecamera may be removed.

However, when, for example, the focal distance of a scanning lens suchas an Fθ lens mounted in the optical scanning device 6 is long, the beamwidth in the main scanning direction D1 increases after the laser beampasses through the aperture 92. When the size of the camera is smallrelative to the width of the laser beam in the main scanning directionD1, the end portions of the laser beam in the main scanning direction D1may not be included in a photographed image P1 taken by the camera, asshown in FIG. 25A. It is noted that, as shown in FIGS. 25A-25D, thecamera is disposed in the optical scanning device 6 in the state wherethe left-right direction of the photographed image P1 is parallel to themain scanning direction D1, and the up-down direction thereof isparallel to the sub scanning direction D2. It is noted that, in FIGS.25A-25D, the laser beam is represented by the hatched area.

Here, it may be considered to use a large-size camera to photograph thelaser beam in its entirety in the main scanning direction D1. However,in that case, the setting position of the camera in the optical scanningdevice 6 is restricted when the fixed state of the aperture 92 isadjusted.

On the other hand, the image forming apparatus 10 according to thefourth embodiment described herewith has a configuration where asmall-size camera can be used when the fixed state of the aperture 92 isadjusted. It is noted that the components that are the same as those ofthe image forming apparatus 10 and the optical scanning device 6described in the third embodiment are assigned the same reference signs,and description thereof is omitted.

Specifically, in the image forming apparatus 10 according to the fourthembodiment, as shown in FIG. 26, the aperture 92 includes a cut portion924 in which a blocking member 925 that is described below can beinserted in a direction perpendicular to the longitudinal direction ofthe opening portion 921. Here, the cut portion 924 is an example of thefirst cut portion, and the blocking member 925 is an example of thefirst blocking member. The cut portion 924 is formed at a predeterminedposition such that the center thereof in the main scanning direction D1matches the center of the opening portion 921 in the main scanningdirection D1. The cut portion 924 is an indent portion formed on thesurface (namely, the front surface) of the aperture 92 on the downstreamside in the emission direction of the laser beam, and does not passthrough the aperture 92 in a direction along the optical axis of thelaser beam. As a result, the cut portion 924 does not affect theperformance of the opening portion 921 of the aperture 92 in restrictingthe width of the laser beam.

As shown in FIG. 27, the blocking member 925 which is in the shape of along cylinder can be attached to and detached from the cut portion 924,wherein the blocking member 925 blocks the laser beam emitted from thelaser diode 614A. Here, when the laser beam after passing through theopening portion 921 is photographed in the state where the blockingmember 925 is inserted in the cut portion 924, in the photographed imageP1 taken by the camera, a part of the laser beam emitted from the laserdiode 614A is blocked by the blocking member 925, as shown in FIG. 25B.At this time, a blocked area B1 that is formed in the laser beam by theblocking member 925 has a predetermined relationship with the openingportion 921 of the aperture 92. That is, the center of the openingportion 921 in the longitudinal direction thereof matches the center ofthe blocked area B1 in the same direction. It is noted that a borderline between the blocked area B1 and the laser beam forms a line segmentthat is perpendicular to the longitudinal direction of the openingportion 921.

With the above-described configuration, it is possible to identify thecenter position of the laser beam in the main scanning direction D1,based on the photographed image P1. More specifically, the centerposition of the laser beam is where the center of a width w2 passesthrough the center between the border lines of the blocked area B1 withthe laser beam, wherein the width w2 extends in a directionperpendicular to the border lines. As a result, even when one or bothends of the laser beam are not included in the photographed image takenby the camera as shown in FIG. 25B, it is possible, by referring to theblocked area B1, to identify the center position of the laser beam, andadjust with ease the fixed position of the aperture 92 in the mainscanning direction D1 (the left-right direction).

In addition, as shown in FIG. 28, in the image forming apparatus 10according to the fourth embodiment, the opening portion 911 may includecut portions 914 in which a blocking member 915 that is described belowcan be inserted in a direction parallel to the longitudinal direction ofthe opening portion 911. Here, the cut portions 914 are an example ofthe second cut portion, and the blocking member 915 is an example of thesecond blocking member. The cut portions 914 are formed at apredetermined position such that the center thereof in the sub scanningdirection D2 matches the center of the opening portion 911 in the subscanning direction D2. The cut portions 914 are indent portions formedon the surface (namely, the front surface) of the aperture 91 on thedownstream side in the emission direction of the laser beam, and doesnot pass through the aperture 91 in a direction along the optical axisof the laser beam. As a result, the cut portions 914 do not affect theperformance of the opening portion 911 of the aperture 91 in restrictingthe width of the laser beam.

As shown in FIG. 29, the blocking member 915 which is in the shape of along cylinder can be attached to and detached from the cut portions 914,wherein the blocking member 915 blocks the laser beam emitted from thelaser diode 614A. Here, when the laser beam after passing through theopening portion 911 is photographed in the state where the blockingmember 915 is inserted in the cut portions 914, in the photographedimage P1 taken by the camera, a part of the laser beam is blocked by theblocking member 915, as shown in FIG. 25C. At this time, a blocked areaB2 that is formed in the laser beam by the blocking member 915 has apredetermined relationship with the opening portion 911 of the aperture91. That is, the longitudinal direction of the opening portion 911 andthe longitudinal direction of the blocked area B2 are parallel to eachother, and a border line between the blocked area B2 and the laser beamforms a line segment that is parallel to the longitudinal direction ofthe opening portion 911.

With the above-described configuration, it is possible to identify theinclination of the laser beam based on the photographed image P1. As aresult, even when one or both ends of the laser beam are not included inthe photographed image taken by the camera as shown in FIG. 25D, it ispossible, by referring to the blocked area B2, to identify theinclination of the laser beam, and adjust with ease the rotationposition of the aperture 91 rotated around the pivoting axis of theaperture 91.

As described above, according to the image forming apparatus 10 of thefourth embodiment, it is possible to use a small-size camera when thefixed state of the aperture 91 and the aperture 92 is adjusted,resulting in relaxation of the restriction made to the setting positionof the camera in the optical scanning device 6.

More specifically, in the optical scanning device 6 of the fourthembodiment, the following work process is executed in the work processexecuted as the fixing method of the apertures 91 and the aperture 92.

First, in the steps S11-S14, the laser beam after passing through theopening portion 911 is photographed by a camera installed at apredetermined position, in the state where the blocking member 915 isinserted in the cut portions 914 of the aperture 91. Next, theinclination of the laser beam after passing through the opening portion911 is identified based on the photographed image taken by the camera.Subsequently, the rotation position of the aperture 91 in the supportmember 93 is adjusted based on the identified inclination of the laserbeam. In addition, the position of the support member 93 in the subscanning direction D2 is adjusted based on the photographed image takenby the camera.

Next, in the steps S15-S16, the blocking member 915 is removed from thecut portions 914, and the laser beam after passing through the openingportion 921 is photographed by the camera installed at the predeterminedposition, in the state where the blocking member 925 is inserted in thecut portion 924 of the aperture 92. Subsequently, the center position ofthe laser beam in the longitudinal direction (the main scanningdirection D1) of the opening portion 921, after passing through theopening portion 921, is identified based on the photographed image takenby the camera. The fixed state of the aperture 92 is then adjusted basedon the identified center position of the laser beam in the longitudinaldirection of the opening portion 921.

It is noted that the laser beam after passing through the openingportion 921 may be photographed by the camera, in the state where theblocking member 915 is inserted in the cut portions 914 and the blockingmember 925 is inserted in the cut portion 924, and the rotation positionof the apertures 91 and the fixed state of the aperture 92 may beadjusted. In that case, for example, the camera may be disposed betweenthe cylindrical lens 77 and the polygon mirror 62. This allows, in thephotographed image taken by the camera, both the blocked area B1 and theblocked area B2 to be formed in the laser beam.

It is to be understood that the embodiments herein are illustrative andnot restrictive, since the scope of the disclosure is defined by theappended claims rather than by the description preceding them, and allchanges that fall within metes and bounds of the claims, or equivalenceof such metes and bounds thereof are therefore intended to be embracedby the claims.

The invention claimed is:
 1. An optical scanning device comprising: alight source configured to emit a plurality of laser beams; a scanningmember configured to deflect and scan the laser beams emitted from thelight source; a converging lens configured to converge the laser beamsemitted from the light source, on a deflection surface of the scanningmember; a first aperture provided between the converging lens and thescanning member and including a first opening portion configured torestrict a beam path width in a main scanning direction of the laserbeams emitted from the light source; a second aperture provided betweenthe light source and the converging lens and including a second openingportion and a cylindrical portion, the second opening portion beingconfigured to restrict a beam path width in a sub scanning direction ofthe laser beams emitted from the light source and being formed in thecylindrical portion; and a support member including a cylindersupporting portion that pivotably supports the cylindrical portion ofthe second aperture, further comprising: a first base portion to whichthe first aperture is fixed by adhesion fixing; and a second baseportion to which the support member is fixed by adhesion fixing, whereinthe first base portion includes a first pass-through portion that isformed to pass through between a front surface and a rear surface of thefirst base portion and allows the first aperture to move in the mainscanning direction, and the second base portion includes a secondpass-through portion that is formed to pass through between a frontsurface and a rear surface of the second base portion and allows thesupport member to move in the sub scanning direction.
 2. The opticalscanning device according to claim 1, wherein the first apertureincludes a first cut portion in which a first blocking member thatblocks the laser beams is inserted in a detachable manner in a directionperpendicular to a longitudinal direction of the first opening portion,at a predetermined position of the first opening portion.
 3. The opticalscanning device according to claim 2, wherein the first cut portion isan indent portion formed on a surface of the first aperture on adownstream side in an emission direction of the laser beams.
 4. Theoptical scanning device according to claim 1, wherein the secondaperture includes a second cut portion in which a second blocking memberthat blocks the laser beams is inserted in a detachable manner in adirection parallel to a longitudinal direction of the second openingportion, at a predetermined position of the second opening portion. 5.The optical scanning device according to claim 4, wherein the second cutportion is an indent portion formed on a surface of the second apertureon a downstream side in an emission direction of the laser beams.
 6. Animage forming apparatus comprising the optical scanning device accordingto claim 1.